Production of genetically modified pigs expressing human insulin and C-peptide as a source of islets for xenotransplantation

Diabetes current and future translatable therapies

Diabetes is one of the major diseases and concerns of public health systems that affects over 200 million patients worldwide. It is estimated that 90% of these patients suffer from diabetes type 2, while 10% present diabetes type 1. This type of diabetes and certain types of diabetes type 2, are characterized by dysregulation of blood glycemic levels due to the total or partial depletion of insulin-secreting pancreatic β-cells. Different approaches have been proposed for long-term treatment of insulin-dependent patients; amongst them, cell-based approaches have been the subject of basic and clinical research since they allow blood glucose level sensing and in situ insulin secretion. The current gold standard for insulin-dependent patients is on-demand exogenous insulin application; cell-based therapies aim to remove this burden from the patient and caregivers. In recent years, protocols to isolate and implant pancreatic islets from diseased donors have been developed and tested in clinical trials. Nevertheless, the shortage of donors, along with the need of immunosuppressive companion therapies, have pushed researchers to focus their attention and efforts to overcome these disadvantages and develop alternative strategies. This review discusses current tested clinical approaches and future potential alternatives for diabetes type 1, and some diabetes type 2, insulin-dependent patients. Additionally, advantages and disadvantages of these discussed methods.

Bioprinted 3D Bionic Scaffolds with Pancreatic Islets as a New Therapy for Type 1 Diabetes-Analysis of the Results of Preclinical Studies on a Mouse Model

Recently, tissue engineering, including 3D bioprinting of the pancreas, has acquired clinical significance and has become an outstanding potential method of customized treatment for type 1 diabetes mellitus. The study aimed to evaluate the function of 3D-bioprinted pancreatic petals with pancreatic islets in the murine model. A total of 60 NOD-SCID (Nonobese diabetic/severe combined immunodeficiency) mice were used in the study and divided into three groups: control group; IsletTx (porcine islets transplanted under the renal capsule); and 3D bioprint (3D-bioprinted pancreatic petals with islets transplanted under the skin, on dorsal muscles). Glucose, C-peptide concentrations, and histological analyses were performed. In the obtained results, significantly lower mean fasting glucose levels (mg/dL) were observed both in a 3D-bioprint group and in a group with islets transplanted under the renal capsule when compared with untreated animals. Differences were observed in all control points: 7th, 14th, and 28th days post-transplantation (129, 119, 118 vs. 140, 139, 140; p < 0.001). Glucose levels were lower on the 14th and 28th days in a group with bioprinted petals compared to the group with islets transplanted under the renal capsule. Immunohistochemical staining indicated the presence of secreted insulin-living pancreatic islets and neovascularization within 3D-bioprinted pancreatic petals after transplantation. In conclusion, bioprinted bionic petals significantly lowered plasma glucose concentration in studied model species.

Heterogenous expression of endocrine and progenitor cells within the neonatal porcine pancreatic lobes-Implications for neonatal porcine islet xenotransplantation

Neonatal porcine islets (NPIs) are a source of islets for xenotransplantation. In the pig, the pancreatic lobes remain separate, thus, when optimizing NPI isolation, the pancreatic lobes included in the pancreatic digest should be specified. These lobes are the duodenal (DL), splenic (SL) and connecting (CL) lobe that correspond to the head, body-tail, and uncinate process of the human pancreas. In this study we are the first to evaluate all three neonatal porcine pancreatic lobes and NPIs isolated from these lobes. We report, a significant difference in endocrine and progenitor cell composition between lobes, and observed pancreatic duct glands (PDG) within the mesenchyme surrounding exocrine ducts in the DL and CL. Following in vitro differentiation, NPIs isolated from each lobe differed significantly in the percent increase of endocrine cells and final cell composition. Compared to other recipients, diabetic immunodeficient mice transplanted with NPIs isolated from the SL demonstrated euglycemic control as early as 4 weeks (p < 0.05) and achieved normoglycemia by 6 weeks post-transplant (p < 0.01). For the first time we report significant differences between the neonatal porcine pancreatic lobes and demonstrate that NPIs from these lobes differ in xenograft function.

Genetically Engineered Porcine Organs for Human Xenotransplantation

Xenotransplantation holds a promising future for many patients, especially those with end-stage renal disease or uncontrollable serum glucose levels. Porcine organs are viewed as the perfect candidate for a source of xenografts. However, the recipient's immunity, incompatibility of biologic systems, and transfer of new pathogenic organisms are all obstacles to clinical xenotransplantation, in addition to the risk of zoonosis and xenoantigens. Genetic modification of pigs using clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated protein 9 (Cas9) resulted in the production of porcine endogenous retrovirus (PERV)-free offsprings with the consequent removal of many clinical complications post-transplantation. Such as minimizing both acute and chronic inflammation, in addition to suppressing rejection reactions, which may prolong graft survival. To build on these recent successes, it is important to look at the limits of genetic engineering and develop ways to advance the field of xenotransplantation and reverse xenotransplantation clinical applications forward. Still, significant problems remain with clinical human xenotransplantation; future work should focus on developing an ideal genetically engineered swine donor source that can improve long-term graft survival and suppress the immune system in a clinically useful way.

Modulating streptococcal phenotypes using signal peptide analogues

Understanding bacterial communication mechanisms is imperative to improve our current understanding of bacterial infectivity and find alternatives to current modes of antibacterial therapeutics. Both Gram-positive and Gram-negative bacteria use quorum sensing (QS) to regulate group behaviours and associated phenotypes in a cell-density-dependent manner. Group behaviours, phenotypic expression and resultant infection and disease can largely be attributed to efficient bacterial communication. Of particular interest are the communication mechanisms of Gram-positive bacteria known as streptococci. This group has demonstrated marked resistance to traditional antibiotic treatment, resulting in increased morbidity and mortality of infected hosts and an ever-increasing burden on the healthcare system. Modulating circuits and mechanisms involved in streptococcal communication has proven to be a promising anti-virulence therapeutic approach that allows managing bacterial phenotypic response but does not affect bacterial viability. Targeting the chemical signals bacteria use for communication is a promising starting point, as manipulation of these signals can dramatically affect resultant bacterial phenotypes, minimizing associated morbidity and mortality. This review will focus on the use of modified peptide signals in modulating the development of proliferative phenotypes in different streptococcal species, specifically regarding how such modification can attenuate bacterial infectivity and aid in developing future alternative therapeutic agents.

Current status of porcine islet xenotransplantation

PURPOSE OF REVIEW

Human islet transplantation has proven to be a highly effective treatment for patients with labile type 1 diabetes mellitus, which can free patients from daily glucose monitoring and insulin injections. However, the shortage of islet donors limits its' broad application. Porcine islet xenotransplantation presents a solution to the donor shortage and recent advances in genetic modification and immunosuppressive regimens provide renewed enthusiasm for the potential of this treatment.

RECENT FINDINGS

Advances in genetic editing technology are leading to multigene modified porcine islet donors with alterations in expression of known xenoantigens, modifications of their complement and coagulation systems, and modifications to gain improved immunological compatibility. Recent NHP-based trials of costimulation blockade using CD154 blockade show promising improvements in islet survival, whereas results targeting CD40 are less consistent. Furthermore, trials using IL-6 receptor antagonism have yet to demonstrate improvement in glucose control and suffer from poor graft revascularization.

SUMMARY

This review will detail the current status of islet xenotransplantation as a potential treatment for type I diabetes mellitus, focusing on recent advances in porcine xenogeneic islet production, assessment in nonhuman primate preclinical models, the outcome of human clinical trials and review barriers to translation of xenoislets to the clinic.

The Influence of the Flow of Detergent and Donor Characteristics on the Extracellular Matrix Composition After Human Pancreas Decellularization

INTRODUCTION

The extracellular matrix (ECM) consists, among others, of polysaccharides, glycosaminoglycans, and proteins. It is being increasingly used in tissue bioengineering. Obtaining ECM of the highest quality through decellularization is a big challenge because of some differences in organ structure. To deprive organs of the cellular part, chemical, enzymatic, or mechanical methods are used. After decellularization, we get a scaffold made of a variety of proteins, and it is the role of these proteins that can significantly affect the maintenance of the spatial structure and be a suitable environment for cells to rebuild a specific organ.

AIM

Estimation of the detergent (Triton X-100) flow parameters and anthropometric donors' decellularization process accuracy on the final ECM composition.

MATERIALS

Five human pancreata, rejected from transplantation, were used for decellularization. All organs were harvested from brain-dead donors age 13 to 60 years.

METHODS

Decellularization was carried out using the flow method with Triton X-100 as an active agent. The experiment compared 5 different flow values. After decellularization, an assessment of the final DNA concentration and the protein composition was performed. Results were compared to anthropometric data of donors. In addition, a microscopic analysis was also carried out.

RESULTS

The best results were obtained using a flow of 120 mL/minute. A higher detergent flow was associated with a lower concentration of residual DNA in scaffold. Analysis of the protein profile with anthropometric data has shown that LAM A2 was increasing with age and LAMA5 was decreasing. Being overweight was associated with a higher proportion of COL1 and 4 and a smaller proportion of COL6.